Home > Research > Publications & Outputs > Extreme Birkeland Currents Are More Likely Duri...


Text available via DOI:

View graph of relations

Extreme Birkeland Currents Are More Likely During Geomagnetic Storms on the Dayside of the Earth

Research output: Contribution to Journal/MagazineJournal articlepeer-review

  • John C. Coxon
  • Gareth Chisham
  • Mervyn P. Freeman
  • Colin Forsyth
  • Maria‐Theresia Walach
  • Kyle R. Murphy
  • Sarah K. Vines
  • Brian J. Anderson
  • Andrew W. Smith
  • Alexandra R. Fogg
Article numbere2023JA031946
<mark>Journal publication date</mark>31/12/2023
<mark>Journal</mark>Journal of Geophysical Research: Space Physics
Issue number12
Publication StatusPublished
Early online date12/12/23
<mark>Original language</mark>English


We examine the statistical distribution of large‐scale Birkeland currents measured by the Active Magnetosphere and Planetary Electrodynamics Response Experiment in four unique categories of geomagnetic activity for the first time: quiet times, storm times, quiet‐time substorms, and storm‐time substorms. A novel method is employed to sort data into one of these four categories, and the categorizations are provided for future research. The mean current density is largest during substorms and its standard deviation is largest during geomagnetic storms. Current densities which are above a low threshold are more likely during substorms, but extreme currents are far more likely during geomagnetic storms, consistent with a paradigm in which geomagnetic storms represent periods of enhanced variability over quiet times. We demonstrate that extreme currents are most likely to flow within the Region 2 current during geomagnetic storms. This is unexpected in a paradigm of the current systems in which Region 1 current is generally larger.